Comparing Adjuvant Chemotherapy Alone and Adjuvant Chemotherapy with Radiation Therapy in Treating Colon Cancer after Successful Surgery (A Phase III Study)
North Central Cancer Treatment Group through the NCI-sponsored Cancer Cooperative Group Program
Purpose of the Study
The purpose of this study was to find out whether adding radiation therapy to chemotherapy following colon cancer surgery would improve the outcome of treatment for patients with colon cancer.
Overall survival was similar among patients who received chemotherapy alone (62 percent were still alive after five years) and those who had chemotherapy and radiation therapy combined (58 percent five-year survival). While this was one of the largest studies of adjuvant radiation therapy to treat colon cancer, the study did not have as many eligible participants as planned and this limited the power of the study to demonstrate a difference between the two forms of treatment.
No further studies are planned on the value of adjuvant radiation therapy for colon cancer. As a result of the findings of this study, most physicians will not use adjuvant radiation therapy for colon cancer.
Number of Participating Patients
187 patients were fully evaluable
Patients entered in the study had colon cancer that had been completely removed surgically within the previous 21 to 36 days. There was a high risk of recurrence of their cancer, based on the location and extent of the tumor, involvement of nearby organs, or lymph node involvement.
Patients were randomly assigned to receive either chemotherapy using fluorouracil and levamisole or chemotherapy using these drugs plus radiation therapy. Both groups started treatment with levamisole taken by mouth three times daily for three days. This was repeated every 14 days for one year. Fluorouracil was given in a vein to both groups on five consecutive days, beginning with the first day of levamisole therapy. Patients assigned to receive chemotherapy without radiation treatment had weekly doses of fluorouracil in a vein starting 28 days after their first dose and continuing for one year. Patients who received radiation therapy in addition to chemotherapy began radiation treatment 28 days after their first fluorouracil dose. They were given radiation in 25 treatments, for a total dose of 45 Gy. Patients received fluorouracil in a vein the first three and last three days that they received radiation treatment. Weekly treatment with fluorouracil continued starting 28 days after completion of radiation treatment, and continued for one year. Patients were evaluated at 12, 15, 18 and 21 months after the start of treatment, then every six months for five years and annually for eight years.
More patients in the chemotherapy plus radiation group experienced serious side effects (54 percent) than the group that received chemotherapy alone (42 percent). The difference reflects a higher rate of problems affecting blood counts in the group that received radiation (23 percent) compared with the chemotherapy-only group (11 percent). The most common side effect not related to blood cell problems was diarrhea, experienced by 20 percent of patients in the radiation group, compared to 13 percent in the chemotherapy-only group. Two treatment-related deaths occurred, one in each group. A patient in the chemotherapy plus radiation group died of infection after white blood cell counts were lowered; another patient in the chemotherapy only group experienced liver failure, believed to be caused by the chemotherapy drugs.
Additional Information at ClinicalTrials.gov